This invention relates to the field of dynamic sealing of a fluid or fluids between coaxial shafts that experience relative rotation between one another. More particularly the invention is directd to an improved seal applicable as an intershaft air-oil seal in counterrotating or coratating multiple spool gas turbine engines.
Among the features desired in a coaxial shaft seal for use in turbines are low drag, ability to maintain centering throughout a wide range of temperatures and rotational speeds, allowance for axial movements between the shafts withoout need for springs, and ability to achieve optimal control of net axial pressure forces acting on the sealing element or elements. Prior art seals have provided some of those features individually, or combinations of some at the expense of others.